Abrasive tool



July 31, 1962 H. E. cooK ABRAsIvE Toor.

Filed oct. 1o, leso f:l.v......................

JNVENTOR. Aff/@afer 5 c ook lUnited States Patent Office 3,646,709 Patented July 31, 1962 This invention relates to abrasive tools and particularly to such tools which utilize replaceable flexible pads or discs made of abrasive materials.

Abrasive tools utilizing replaceable flexible pads or discs are commonly employed for the finishing, polishing and chamfering of holes stamped in sheet metal Work; for the finishing or polishing of the interiors of tubes or cylinders; for `general disc grinding, blending and finishing on molds, dies, and other surface areas; and for other similar uses. Such abrasive tools utilize discs made up of one or more layers of abrasive coated cloth, liber or paper or pads made up of layers of abrasive material folded into square or cruciform shape. A conventional structure comprises a mandrel having a threaded end that engages a threaded grommet on the flexible pador disc. Such a construction has the distinct disadvantage in that in use the deformed grommet engages the portion of the mandrel at the base of a flange located at the base of a threaded section and tends to bind due to a spring-locking action created by torque generated by the power ttool in which the mandrel is mounted. This makes it extremely dithcult to remove the pad in order to replace it. In most instances, a tool must be used to break the connection between the grommet and the mandrel.

It is an object of this invention to provide a novel abrasive tool which includes a removable disc or pad assembly that can be readily removed and replaced.

It is a further object of the invention to provide such a disc or pad assembly that can be replaced without the use of tools.

It is a further object of the invention to provide a novel disc or pad assembly.

It is a further object of the invention to provide a novel mandrel.

In the drawings:

FIG. l is a part sectional elevation of an abrading tool embodying the invention shown along the line 1 1 in FIG. 3. f

FIG. 2 is an exploded view of the parts of the tool prior to assembly.

FIG. 3 is a perspective view of the abrasive tool.

FIG. 4 is a perspective View of a modified form of abrasive tool.

FIG. 5 is a part sectional elevation similar to FIG. 1 of a modified form of abrading tool.

Referring to FIGS. l, 2 and 3, the abrasive tool 10 embodying the invention comprises a mandrel 11 and a removable abrasive pad or disc assembly 12. The mandrel is adapted to be inserted in a drive mechanism such as a power drill in order that it can be rotated and, in turn, rotate the pad or disc 13 which is part of the pad assembly 12.

Mandrel 11 comprises an enlarged cylindrical end 14 that is formed with an axial -threaded opening 15. The upper surface 16 of the enlarged head 14 is flat except for a peripheral circular rim 17 that extends axially away from the surface 16.

Abrasive pad assembly 12 comprises a body member 18 that includes a threaded shank 19 that is adapted to engage the threaded opening of the mandrel 11, a central radially extending flange 20 of substantially uniform axial thickness and a hollow rivet portion 21. The surfaces 23, 24 of the ange 2li are substantially flat and parallel. Disc 13 may be of any conventional type such asV one or more flexible layers of -abrasive coated cloth, liber -or paper; The disc is formed With an open ing 25 through which lthe rivet portion 21 is adapted to extend after which the rivet portion 21 is deformed asA at 26 to hold the disc 13 in position and in contact Wit the surface 23 of the flange 2li.

In order to mount rthe abrasive assembly 12 on the mandrel 11, the shank 19 is threaded into the opening 15 bringing the surface 24 into engagement with the end of the rim 17 on the mandrel 11. The'threads on shank 19 and opening 15 are so related to the direction of rotation of the mandrel 11 that as the mandrel is rotated by the device which `drives it, the shank 19 tends to thread further into the opening 15. For example, as shown in FIG. 1, if the -direction of rotation of the mandrel 11 is in a clockwise direction as viewed from the free lend `of the mandrel, the threads on the shaft 19 and opening 15 are counterclockwise or right hand.

In use, the mandrel 11 is rotated clockwise, as viewed from the free end of mandrel 11, rotating the assembly 12, and, in turn, the pad 13. The contact of the rim 17 with an annular area of the surface 24 provides a limited area of contact so that it is easy to remove the pad assembly 12 for replacement by rotating the pad assembly 12 clockwise, as viewed from the free end of mandrel 11,

While holding the mandrel stationary, all operations being performed by hand. The mandrel 11 may be knurled to vfacilitate grasping it by hand.

Although I do not wish to be bound by the theory involved, in my opinion, the ease of removal of the pad assembly 12is due to the fact that a stressing or flexing of the flange 21D occurs between the shank 15 andthe rim 17 providing suflicient force to hold the assembly 12 on the mandrel. However, the fact that the force is applied to a minimum area, namely, the lip of rim 17, permits the engagement to be easily broken.

As shown in FIG. 4, instead of using a disc such as shown in. FIG. 3, a pad 27 comprising a plurality ofy layers of abrasive coated paper or cloth may be used on the mandrel 11.

A modified form of abrasive tool is shown in FIG. 5'.

This form of `tool comprises a mandrel 31 and a removable abrasive disc assembly 32. Mandrel 31 includes an enlarged cylindrical end 33 that is formed with an axial threaded opening 34 having a stepped shoulder 35 at the upper end thereof and a flat surface 36 surrounding the shoulder 35. Abrasive pad assembly 32 comprises a body member 37 which is identical in construction to the body member 18. When the abrasive pad assembly 32 is mounted on the mandrel 31 by threading lthe shank of the assembly into the opening 34, the surface 24 of the abrasive pad assembly engages the shoulder 35, there-by contacting the shoulder along a limited area. At the same time the undersurface of the abrasive disc 39a of the assembly engages the surface 36 of the head 33 providing a backing. This construction provides the same beneficial effects of the previous form of the invention, namely, the ready removability of the abrasive disc assembly, but, at the same time, provides a backing to the abrasive disc 38 giving it support and preventing its easy tearing in the event that ths disc is relatively thin.

The term pad as used herein is intended to cover pads, discs or other similar flexible abrasive devices whether or single or multiple ply.

I claim:

1. An abrading tool comprising a mandrel having an axially extending threaded opening in one end thereof, an abrasive pad assembly removably mounted on said mandrel, said assembly comprising a body, a threaded shank engaging said threaded opening in said mandrel, a pad,

and means for fixing said pad on said body, said mandrel having a continuous shoulder surrounding the opening in the end thereof and engaging said body of said abrasive pad assembly.

2. In an abrasive tool, the combination comprising a mandrel having an axial threaded opening in one end thereof, and an abrasive pad assembly removably mounted on said mandrel, said assembly `comprising a body having a threaded shank engaging the threaded opening in said mandrel, a central ange portion extending radially outwardly from said shank, a pad, and means on said ybody fixing said pad on said body, said mandrel including a peripheral axially extending rim engaging said central ange portion at a point spaced from the axis of said opening.

3. In an abrasive tool the combination comprising a mandrel having a cylindrical head and an axial threaded opening therein, and an abrasive pad assembly, said pad assembly comprising a body having a threaded shank engaging the opening in said mandrel, a central ange extending radially outwardly from said shank and spaced from the end thereof, said mandrel having an axially extending peripheral rim on said head engaging the flange portion of said body, a pad, said body having a rivet portion extending axially through an opening in said pad, said rivet portion being deformed to hold said pad on said body.

4. In an abrasive tool the combination comprising a mandrel having a cylindrical head and an axial threaded opening therein, and an abrasive pad assembly, said pad assembly comprising a body having a threaded shank engaging the opening in said mandrel, a central ange of substantially uniform axial thickness extending radially outwardly from said shank and spaced from the end thereof, said mandrel having an axially extending peripheral rim on said head engaging the ange portion X of said body, a pad, said 'body having a rivet portion extending axially through an opening in said pad, said rivet portion being deformed to hold said pad on said body.

5. An abrasive pad assembly comprising a body having a threaded shank, a central radially extending flange extending outwardly from one end of said shank, a pad having a central opening therein, and a rivet portion extending axially in the opposite direction from said shank lthrough said pad, said rivet portion being deformed to hold said pad on said body in engagement with said flange.

6. An abrasive pad assembly comprising a body having a threaded shank, a central radially extending flange of substantially uniform thickness extending outwardly from one end of said shank, a pad having a central opening therein and a rivet portion extending axially in the opposite direction from said shank through said pad, said rivet portion being deformed to hold said pad on said body in engagement with said flange.

7. An abrading tool comprising a mandrel having an axially extending opening in one end thereof, an abrasive pad assembly removably mounted on said mandrel, said assembly comprising a body, a threaded shank engaging said threaded opening in said mandrel, a pad, and means for fixing said pad on said body, said mandrel having a continuous shoulder surrounding the opening in the end thereof and engaging said body of said abrasive pad assembly, said mandrel having a continuous peripheral surface spaced radially from the shoulder and surrounding the opening and adapted to engage and support the pad.

Link Jan. 17, 19ll Blair Feb. 18, 1936 

